1. Field of the Invention
The present invention relates generally to electrical power distribution equipment and, more particularly, to a vacuum interrupter for a power distribution system.
2. Description of the Related Art
Circuit breakers and other power distribution equipment are well known in the relevant art. Circuit breakers are typically configured to interrupt current upon the occurrence of one or more predetermined conditions. Each pole of a circuit breaker typically includes a pair of contacts that are separable from one another in order to interrupt current flowing therethrough.
It is known, however, that electricity can have a tendency to arc between separated contacts. In the event that such an arc occurs, power still continues to flow through the pole with the arc, which is an undesirable situation that is preferably avoided. Additionally, electricity arcing between separated contacts has a tendency to vaporize portions of the contacts, with the result that the contacts are unable to make good electrical connections with one other thereafter. It is thus known to provide vacuum interrupters in certain applications to resist the formation of arcs between separated contacts. Such vacuum interrupters typically include a stationary contact and a movable contact within an evacuated region of a container, whereby the substantial absence of air within the evacuated region resists the formation of arcs between the contacts during separation and during closure thereof. It is also known to provide similar interrupters which include a dielectric gas such as sulfur hexafluoride within a container in the vicinity of the contacts instead of employing an evacuated region in the container.
As is also known in the relevant art, a substantial engagement force must be maintained on the movable contact to keep the contacts engaged with one another when power is being transmitted therethrough. Known interrupters of the type described above thus have included a drive mechanism that can apply a large compressive force to the movable contact and that can pull the contacts apart under appropriate circumstances. In order to isolate the drive mechanism from the high voltage circuit that includes the movable contact, the drive mechanism typically is spaced from the container and is operatively connected with the movable contact by an elongated non-conductive rod. For instance, in particularly high voltage applications, the electrified portions of the container may be spaced twenty-two inches from a base that carries the drive mechanism. Since the compressive force required to retain the movable contact against the stationary contact is transmitted from the drive unit to the movable contact through the elongated rod, the rod often has a tendency to bow a significant amount.
Such bowing of the rod is undesirable for a number of reasons. For instance, it is often desired that the movable contact be moved a fixed distance away from the stationary contact when the contacts are separated. Bowing of the rod results in substantial imprecision in the specific position of the movable contact. Such bowing can also breach an expandable seal that seals the space between the container and the rod. Moreover, a large bow in the rod will have a tendency to delay slightly the separation of the movable contact from the fixed contact since the bow in the rod creates a type of slack that must be taken up before the contacts can be separated. Furthermore, the rod moves at a speed in the range of about 1.5 to 2 meters per second during separation and closing. The speed with which the rod bows at the time the contacts are closed causes the rod to elastically flap about, which delays the creation of a solid connection between the contacts and/or results in excessive contact bounce.
It is thus desired to provide an improved electrical interrupter apparatus that overcomes the problems associated with known push-to-close interrupters.
The present invention successfully meets and exceeds these and other needs. An improved electrical interrupter apparatus includes a stationary contact and a movable contact within an enclosed region, with the movable contact being operatively connected with a drive unit that employs a pull-to-close mechanism to engage the movable contact with the stationary contact. When the contacts are desired to be closed, the drive unit applies a tensile force to an elongated rod that extends between the drive unit and a crank mechanism, which converts the tensile force in the rod into a compressive force applied to the movable contact.
An aspect of the present invention is to provide an improved electrical interrupter apparatus that applies a tensile force to an elongated rod in order to close a pair of electrical contacts.
Another aspect of the present invention is to provide an improved electrical interrupter apparatus that includes a crank which can transform a tensile force into a compressive force applied to a movable contact.
Another aspect of the present invention is to provide an improved electrical interrupter apparatus that employs a pair of contacts in a vacuum region and that is capable of moving one of the contacts substantially precise distances.
Another aspect of the present invention is to provide an improved electrical interrupter apparatus that employs rods or links that are substantially free of bowing when a compressive force is applied to a movable contact.
Another aspect of the present invention is to provide an improved electrical interrupter apparatus that reliably and rapidly opens and closes a set of contacts within a vacuum vacuum bottle.
These and other aspects of the present invention are provided by an electrical interrupter apparatus, the general nature of which can be stated as including an interruption device including an interior and having an enclosed region within at least a portion of the interior, a stationary contact disposed within the enclosed region, and a movable contact disposed within the enclosed region. The movable contact is movable between a closed position and an open position, and the movable contact is engaged with the stationary contact in the closed position. The movable contact is spaced from the stationary contact in the open position. The electrical interrupter apparatus further includes a first link operatively connected with the movable contact, a second link, a crank operatively interposed between the first and second links, and a driving system including a drive unit. The drive unit is operatively connected with the second link and is structured to rapidly separate the movable and stationary contacts. One of the first and second links is longer than the other of the first and second links, and the one of the first and second links is in a state of tension when the movable contact is in the closed position.
The driving system may additionally include a return spring that biases the movable contact to the open position. Alternatively, or in addition thereto, the interruption device may include a support, with the crank being pivotably mounted to the support. The enclosed region may be a region of reduced pressure.
Another aspect of the present invention is to provide an electrical interrupter apparatus, the general nature of which can be stated as including an interruption device including an interior and having an enclosed region within at least a portion of the interior, a stationary contact disposed within the enclosed region, and a movable contact disposed within the enclosed region. The movable contact is movable between a closed position and an open position, the movable contact is engaged with the stationary contact in the closed position, and the movable contact is spaced from the stationary contact in the open position. The electrical interrupter apparatus further includes a first link operatively connected with the movable contact, a second link, a crank pivotably mounted to the interruption device, the first and second links each being pivotably mounted to the crank, and a driving system including a drive unit. The drive unit is operatively connected with the second link and is structured to rapidly separate the movable and stationary contacts, and the second link is in a state of tension when the movable contact is in the closed position.
The driving system may additionally include a return spring that biases the movable contact to the open position. Alternatively, or in addition thereto, the interruption device may include a vacuum vacuum bottle and a support, the vacuum vacuum bottle being mounted to the support, the enclosed region being disposed within the vacuum vacuum bottle, and the crank being pivotably mounted to the support.
Another aspect of the present invention is to provide an electrical interrupter apparatus, the general nature of which can be stated as including an interruption device including an interior and having an enclosed region within at least a portion of the interior, a stationary contact disposed within the enclosed region, and a movable contact disposed within the enclosed region. The movable contact is movable between a closed position and an open position, with the movable contact being engaged with the stationary contact in the closed position, and with the movable contact being spaced from the stationary contact in the open position. The electrical interrupter apparatus also includes a first link operatively connected with the movable contact, a second link, a crank operatively interposed between the first and second links, and a driving system including a drive unit. The drive unit is operatively connected with the second link and is structured to rapidly separate the movable and stationary contacts. The first link is in a state of compression when the movable contact is in the closed position, and the second link is in a state of tension when the movable contact is in the closed position. The first and second links are oriented generally parallel with one another.
The first and second links may be mounted on the crank and extend in generally opposite directions away from the crank. The interruption device may include a vacuum vacuum bottle and a support, with the vacuum vacuum bottle being mounted to the support, with the enclosed region being disposed within the vacuum bottle, and with the crank being pivotable mounted to the support. The crank may be pivotable about an axis that is oriented substantially perpendicular to the orientation of the first and second links. The support may include a pair of parallel and spaced apart fins, with the crank including a pair of crank plates, with the crank plates being pivotably mounted to the fins whereby the fins straddle the crank plates, and with each crank plate including a pair of elongated slots spaced apart from one another in generally opposite directions from the axis about which the crank plate rotates, the elongated slots being oriented generally parallel with one another.